The colour of the positive column in a gas discharge tube depends on

Planck’s constant has the dimensions of

The colour of the positive column in a gas discharge tube depends on

If ${n_R}$ and ${n_V}$ denote the number of photons emitted by a red bulb and violet bulb of equal power in a given time, then

A tiny spherical oil drop carrying a net charge $q$ is balanced in still air with vertical uniform electric field of strength $\frac{{81\pi }}{7} imes {10^5}{\rm{V}}{{\rm{m}}^{ - 1}}.$When the field is switched off, the drop is observed to fall with terminal velocity $2 imes {10^{ - 3}}{\rm{m}}{{\rm{s}}^{ - 1}}.$ Given ${\rm{g}} = 9.8{\rm{\;m}}{{\rm{s}}^{ - 2}},$ viscosity of the air =$1.8 imes {10^{ - 5}}{\rm{Ns\;}}{{\rm{m}}^{ - 2}}{\rm{\;and\;the\;density\;of\;oil}} = 900\;{\rm{kg}}\;{{\rm{m}}^{ - 3}},$ the magnitude of $q$ is

The light rays having photons of energy $1.8\;eV$ are falling on a metal surface having a work function $1.2\;eV.$ What is the stopping potential to be applied to stop the emitting electrons

If the energy of photons corresponding to the wavelength of 6000$\mathop A\limits^ \circ$ is $3.2 imes {10^{ - 19}}$ J, the photon energy for a wavelength of 4000$\mathop A\limits^ \circ$ will be

The magnitude of saturation photoelectric current depends upon

When yellow light is incident on a surface, no electrons are emitted while green light can emit. If red light is incident on the surface, then

When green light is incident on the surface of metal, it emits photo-electrons but there is no such emission with yellow colour light. Which one of the colours can produce emission of photo-electrons

The number of photo-electrons emitted per second from a metal surface increases when